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From: Joao Martins <joao.m.martins@oracle.com>
To: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	xen-devel@lists.xenproject.org
Cc: "Ankur Arora" <ankur.a.arora@oracle.com>,
	"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
	"Joao Martins" <joao.m.martins@oracle.com>,
	"Paolo Bonzini" <pbonzini@redhat.com>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Thomas Gleixner" <tglx@linutronix.de>,
	"Ingo Molnar" <mingo@redhat.com>,
	"Borislav Petkov" <bp@alien8.de>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, "Juergen Gross" <jgross@suse.com>,
	"Stefano Stabellini" <sstabellini@kernel.org>
Subject: [PATCH RFC 32/39] xen/balloon: xen_shim_domain() support
Date: Wed, 20 Feb 2019 20:16:02 +0000	[thread overview]
Message-ID: <20190220201609.28290-33-joao.m.martins@oracle.com> (raw)
In-Reply-To: <20190220201609.28290-1-joao.m.martins@oracle.com>

Xen ballooning uses hollow struct pages (with the underlying PFNs being
populated/unpopulated via hypercalls) which are used by the grant logic
to map grants from other domains.

For purposes of a KVM based xen-shim, this model is not useful --
mapping is unnecessary since all guest memory is already mapped in the
KVM host. The simplest option is to just translate grant references to
GPAs (essentially a get_page() on the appropriate GPA.)

This patch provides an alternate balloon allocation mechanism where in
the allocation path we just provide a constant struct page
(corresponding to page 0.) This allows the calling code -- which does a
page_to_pfn() on the returned struct page -- to remain unchanged before
doing the grant operation (which in this case would fill in the real
struct page.)

Co-developed-by: Ankur Arora <ankur.a.arora@oracle.com>
Signed-off-by: Joao Martins <joao.m.martins@oracle.com>
Signed-off-by: Ankur Arora <ankur.a.arora@oracle.com>
---
 arch/x86/kvm/xen-shim.c | 31 +++++++++++++++++++++++++++++++
 drivers/xen/balloon.c   | 15 ++++++++++++++-
 include/xen/balloon.h   |  7 +++++++
 3 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/xen-shim.c b/arch/x86/kvm/xen-shim.c
index 61fdceb63ec2..4086d92a4bfb 100644
--- a/arch/x86/kvm/xen-shim.c
+++ b/arch/x86/kvm/xen-shim.c
@@ -13,11 +13,40 @@
 #include <xen/xen-ops.h>
 #include <xen/events.h>
 #include <xen/xenbus.h>
+#include <xen/balloon.h>
 
 #define BITS_PER_EVTCHN_WORD (sizeof(xen_ulong_t)*8)
 
 static struct kvm_xen shim = { .domid = XEN_SHIM_DOMID };
 
+static int shim_alloc_pages(int nr_pages, struct page **pages)
+{
+	int i;
+
+	/*
+	 * We provide page 0 instead of NULL because we'll effectively
+	 * do the inverse operation while deriving the pfn to pass to
+	 * xen for mapping.
+	 */
+	for (i = 0; i < nr_pages; i++)
+		pages[i] = pfn_to_page(0);
+
+	return 0;
+}
+
+static void shim_free_pages(int nr_pages, struct page **pages)
+{
+	int i;
+
+	for (i = 0; i < nr_pages; i++)
+		pages[i] = NULL;
+}
+
+static struct xen_balloon_ops shim_balloon_ops = {
+	.alloc_pages = shim_alloc_pages,
+	.free_pages = shim_free_pages,
+};
+
 static void shim_evtchn_setup(struct shared_info *s)
 {
 	int cpu;
@@ -65,6 +94,7 @@ static int __init shim_register(void)
 	mutex_init(&shim.xen_lock);
 
 	kvm_xen_register_lcall(&shim);
+	xen_balloon_ops = &shim_balloon_ops;
 
 	/* We can handle hypercalls after this point */
 	xen_shim_domain = 1;
@@ -94,6 +124,7 @@ static void __exit shim_exit(void)
 	xen_shim_domain = 0;
 
 	kvm_xen_unregister_lcall();
+	xen_balloon_ops = NULL;
 	HYPERVISOR_shared_info = NULL;
 	free_page((unsigned long) shim.shinfo);
 	shim.shinfo = NULL;
diff --git a/drivers/xen/balloon.c b/drivers/xen/balloon.c
index ceb5048de9a7..00375fa6c122 100644
--- a/drivers/xen/balloon.c
+++ b/drivers/xen/balloon.c
@@ -138,7 +138,7 @@ enum bp_state {
 
 static DEFINE_MUTEX(balloon_mutex);
 
-struct balloon_stats balloon_stats;
+struct balloon_stats balloon_stats __read_mostly;
 EXPORT_SYMBOL_GPL(balloon_stats);
 
 /* We increase/decrease in batches which fit in a page */
@@ -158,6 +158,9 @@ static DECLARE_DELAYED_WORK(balloon_worker, balloon_process);
 #define GFP_BALLOON \
 	(GFP_HIGHUSER | __GFP_NOWARN | __GFP_NORETRY | __GFP_NOMEMALLOC)
 
+struct xen_balloon_ops *xen_balloon_ops;
+EXPORT_SYMBOL(xen_balloon_ops);
+
 /* balloon_append: add the given page to the balloon. */
 static void __balloon_append(struct page *page)
 {
@@ -589,6 +592,11 @@ int alloc_xenballooned_pages(int nr_pages, struct page **pages)
 	struct page *page;
 	int ret;
 
+	if (xen_shim_domain() && xen_balloon_ops)
+		return xen_balloon_ops->alloc_pages(nr_pages, pages);
+
+	WARN_ON_ONCE(xen_shim_domain());
+
 	mutex_lock(&balloon_mutex);
 
 	balloon_stats.target_unpopulated += nr_pages;
@@ -634,6 +642,11 @@ void free_xenballooned_pages(int nr_pages, struct page **pages)
 {
 	int i;
 
+	if (xen_shim_domain() && xen_balloon_ops)
+		return xen_balloon_ops->free_pages(nr_pages, pages);
+
+	WARN_ON_ONCE(xen_shim_domain());
+
 	mutex_lock(&balloon_mutex);
 
 	for (i = 0; i < nr_pages; i++) {
diff --git a/include/xen/balloon.h b/include/xen/balloon.h
index 4914b93a23f2..9ba6a7e91d5e 100644
--- a/include/xen/balloon.h
+++ b/include/xen/balloon.h
@@ -22,6 +22,13 @@ struct balloon_stats {
 
 extern struct balloon_stats balloon_stats;
 
+struct xen_balloon_ops {
+	int (*alloc_pages)(int nr_pages, struct page **pages);
+	void (*free_pages)(int nr_pages, struct page **pages);
+};
+
+extern struct xen_balloon_ops *xen_balloon_ops;
+
 void balloon_set_new_target(unsigned long target);
 
 int alloc_xenballooned_pages(int nr_pages, struct page **pages);
-- 
2.11.0


  parent reply	other threads:[~2019-02-20 20:19 UTC|newest]

Thread overview: 126+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-02-20 20:15 [PATCH RFC 00/39] x86/KVM: Xen HVM guest support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 01/39] KVM: x86: fix Xen hypercall page msr handling Joao Martins
2019-02-22  1:30   ` Sean Christopherson
2019-02-22 11:47     ` Joao Martins
2019-02-22 12:51     ` Paolo Bonzini
2020-11-30 10:39       ` David Woodhouse
2020-11-30 11:03         ` Paolo Bonzini
2020-11-30 11:27           ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 02/39] KVM: x86/xen: intercept xen hypercalls if enabled Joao Martins
2019-02-21 18:29   ` Sean Christopherson
2019-02-21 20:56     ` Joao Martins
2019-02-22  0:30       ` Sean Christopherson
2019-02-22 12:50         ` Paolo Bonzini
2020-12-01  9:48   ` David Woodhouse
2020-12-01 11:19     ` David Woodhouse
2020-12-02 11:17       ` Joao Martins
2020-12-02 12:12         ` David Woodhouse
2020-12-02  5:19     ` Ankur Arora
2020-12-02  8:03       ` David Woodhouse
2020-12-02 18:20         ` Ankur Arora
2019-02-20 20:15 ` [PATCH RFC 03/39] KVM: x86/xen: register shared_info page Joao Martins
2020-12-01 13:07   ` David Woodhouse
2020-12-02  0:40     ` Ankur Arora
2020-12-02  1:26       ` David Woodhouse
2020-12-02  5:17         ` Ankur Arora
2020-12-02 10:50           ` Joao Martins
2020-12-02 10:44       ` Joao Martins
2020-12-02 12:20         ` David Woodhouse
2020-12-02 20:32           ` Ankur Arora
2020-12-03 10:16             ` David Woodhouse
2020-12-04 17:30               ` Sean Christopherson
2020-12-02 20:33         ` Ankur Arora
2020-12-12 12:07       ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 04/39] KVM: x86/xen: setup pvclock updates Joao Martins
2019-02-20 20:15 ` [PATCH RFC 05/39] KVM: x86/xen: update wallclock region Joao Martins
2019-02-20 20:15 ` [PATCH RFC 06/39] KVM: x86/xen: register vcpu info Joao Martins
2019-02-20 20:15 ` [PATCH RFC 07/39] KVM: x86/xen: register vcpu time info region Joao Martins
2019-02-20 20:15 ` [PATCH RFC 08/39] KVM: x86/xen: register steal clock Joao Martins
2019-02-20 20:15 ` [PATCH RFC 09/39] KVM: x86: declare Xen HVM guest capability Joao Martins
2019-02-20 20:15 ` [PATCH RFC 10/39] KVM: x86/xen: support upcall vector Joao Martins
2020-12-02 11:17   ` David Woodhouse
2020-12-02 13:12     ` Joao Martins
2020-12-02 16:47       ` David Woodhouse
2020-12-02 18:34         ` Joao Martins
2020-12-02 19:02           ` David Woodhouse
2020-12-02 20:12             ` Joao Martins
2020-12-02 20:37               ` David Woodhouse
2020-12-03  1:08             ` Ankur Arora
2020-12-08 16:08             ` David Woodhouse
2020-12-09  6:35               ` Ankur Arora
2020-12-09 10:27                 ` David Woodhouse
2020-12-09 10:51                   ` Joao Martins
2020-12-09 11:39                     ` David Woodhouse
2020-12-09 13:26                       ` Joao Martins
2020-12-09 15:41                         ` David Woodhouse
2020-12-09 16:12                           ` Joao Martins
2021-01-01 14:33           ` David Woodhouse
2021-01-05 12:11             ` Joao Martins
2021-01-05 13:23               ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 11/39] KVM: x86/xen: evtchn signaling via eventfd Joao Martins
2020-11-30  9:41   ` David Woodhouse
2020-11-30 12:17     ` Joao Martins
2020-11-30 12:55       ` David Woodhouse
2020-11-30 15:08         ` Joao Martins
2020-11-30 16:48           ` David Woodhouse
2020-11-30 17:15             ` Joao Martins
2020-11-30 18:01               ` David Woodhouse
2020-11-30 18:41                 ` Joao Martins
2020-11-30 19:04                   ` David Woodhouse
2020-11-30 19:25                     ` Joao Martins
2021-11-23 13:15           ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 12/39] KVM: x86/xen: store virq when assigning evtchn Joao Martins
     [not found]   ` <b750291466f3c89e0a393e48079c087704b217a5.camel@amazon.co.uk>
2022-02-10 12:17     ` Joao Martins
2022-02-10 15:23       ` [EXTERNAL] " David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 13/39] KVM: x86/xen: handle PV timers oneshot mode Joao Martins
2019-02-20 20:15 ` [PATCH RFC 14/39] KVM: x86/xen: handle PV IPI vcpu yield Joao Martins
2019-02-20 20:15 ` [PATCH RFC 15/39] KVM: x86/xen: handle PV spinlocks slowpath Joao Martins
2022-02-08 12:36   ` David Woodhouse
2022-02-10 12:17     ` Joao Martins
2022-02-10 14:11       ` David Woodhouse
2019-02-20 20:15 ` [PATCH RFC 16/39] KVM: x86: declare Xen HVM evtchn offload capability Joao Martins
2019-02-20 20:15 ` [PATCH RFC 17/39] x86/xen: export vcpu_info and shared_info Joao Martins
2019-02-20 20:15 ` [PATCH RFC 18/39] x86/xen: make hypercall_page generic Joao Martins
2019-02-20 20:15 ` [PATCH RFC 19/39] xen/xenbus: xenbus uninit support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 20/39] xen-blkback: module_exit support Joao Martins
2019-02-25 18:57   ` Konrad Rzeszutek Wilk
2019-02-26 11:20     ` Joao Martins
2019-02-20 20:15 ` [PATCH RFC 21/39] KVM: x86/xen: domid allocation Joao Martins
2019-02-20 20:15 ` [PATCH RFC 22/39] KVM: x86/xen: grant table init Joao Martins
2019-02-20 20:15 ` [PATCH RFC 23/39] KVM: x86/xen: grant table grow support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 24/39] KVM: x86/xen: backend hypercall support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 25/39] KVM: x86/xen: grant map support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 26/39] KVM: x86/xen: grant unmap support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 27/39] KVM: x86/xen: grant copy support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 28/39] KVM: x86/xen: interdomain evtchn support Joao Martins
2019-02-20 20:15 ` [PATCH RFC 29/39] KVM: x86/xen: evtchn unmask support Joao Martins
2019-02-20 20:16 ` [PATCH RFC 30/39] KVM: x86/xen: add additional evtchn ops Joao Martins
2019-02-20 20:16 ` [PATCH RFC 31/39] xen-shim: introduce shim domain driver Joao Martins
2019-02-20 20:16 ` Joao Martins [this message]
2019-02-20 20:16 ` [PATCH RFC 33/39] xen/grant-table: xen_shim_domain() support Joao Martins
2019-02-20 20:16 ` [PATCH RFC 34/39] xen/gntdev: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 35/39] xen/xenbus: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 36/39] drivers/xen: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 37/39] xen-netback: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 38/39] xen-blkback: " Joao Martins
2019-02-20 20:16 ` [PATCH RFC 39/39] KVM: x86: declare Xen HVM Dom0 capability Joao Martins
2019-02-20 21:09 ` [PATCH RFC 00/39] x86/KVM: Xen HVM guest support Paolo Bonzini
2019-02-21  0:29   ` Ankur Arora
2019-02-21 11:45   ` Joao Martins
2019-02-22 16:59     ` Paolo Bonzini
2019-03-12 17:14       ` Joao Martins
2019-04-08  6:44         ` Juergen Gross
2019-04-08 10:36           ` Joao Martins
2019-04-08 10:42             ` Juergen Gross
2019-04-08 17:31               ` Joao Martins
2019-04-09  0:35                 ` Stefano Stabellini
2019-04-10  5:50                   ` [Xen-devel] " Ankur Arora
2019-04-10 20:45                     ` Stefano Stabellini
2019-04-09  5:04                 ` Juergen Gross
2019-04-10  6:55                   ` Ankur Arora
2019-04-10  7:14                     ` Juergen Gross
2019-02-20 23:39 ` [Xen-devel] " Marek Marczykowski-Górecki
2019-02-21  0:31   ` Ankur Arora
2019-02-21  7:57   ` Juergen Gross
2019-02-21 12:00     ` Joao Martins
2019-02-21 11:55   ` Joao Martins

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